A lot of draft-dodging strategies sound clever, but the odds are that
the military has anticipated them and has prepared counterstrategies.
Sure, back in grammar school, you could get out of class if you claimed
you had a certain condition (such as a stomachache) and the nurse
couldn't prove that you were lying. The military adopts a higher standard
to prevent malingering; if you can't prove that you do
have a particular disease, then you're okay, and you're off to the
jungle.

A story:

During the Vietnam War, my father and his good friend--along with
about forty other students at their university--were called for
the draft. Now this sort of thing happened all the time at the
university, so the military had arranged for a school bus to take the students
down to the place where they were to be tested.

On the appointed day, my father, his friend (Mr. Jackson), and the
other forty students (except for those who were burning their draft cards
and such) got on the bus. On the long ride downtown, the students were
filled with manic glee--they were scared, sure, but they all knew that
they had the perfect excuse. One was on crutches, one had a back brace,
another had his arm in a sling, another wore an eyepatch, another had
perfected a nervous twitch, and about ten had doctor's notes saying that
they were too sick to serve.

The students quieted down when they actually arrived at the testing
site. My father's number was called, and he went in. He took the
visual-acuity test. His vision, like mine, is abysmal--worse than
20/400--and he wears coke-bottle glasses. They looked at him
suspiciously, checked his eyes with some gadget to make sure he wasn't
faking. He wasn't. They laughed at him, stamped him 4-F, and sent him
back to the waiting room.

Then Mr. Jackson went in. He passed the visual-acuity test without
difficulty. Then he took the test for colorblindness.
Now, you've probably seen these tests before; they consist of a
hodgepodge of little 1-cm dots of varying shades of color. Within the
hodgepodge, some of the dots are arranged to form a digit or a letter.
On one type of card, you can perceive the digit only if you are
colorblind; on the other, you can perceive it only if you are not
colorblind. Typically you get one of each card; that way, if you pass the
visual acuity test but claim you can't see any numbers, they know you're
faking.

The examiner slides a small scope towards Mr. Jackson and sighs.
"All
right, son; look in the eyepiece and tell me what number you see."

The recruiter gives my father's friend a long stare. Without moving his
eyes from Mr. Jackson's face, he slides the scope behind his desk,
replaces the card, slides it back. He picks up a large manual, looks down
at it for a few moments, then glares at my father's friend again.

"All right, son. Look again."

He looked. "Seventy-ei..."

The recruiter reaches across the desk, yanks
the scope out from underneath Mr. Jackson's eyes, grabs his draft card,
stamps it 4-F, and throws it back. "Get out of here, boy!" the recruiter
bellows.

Turns out Mr. Jackson was colorblind...but only in one eye.

My father and his friend were the only two people on the bus going
back.